An organic EL element has recently been attracting wide attention as the light source of an illumination apparatus because the organic EL element emits high-brightness lights using low voltage in various colors depending on the kinds of organic compounds contained therein. Secondly, it is easy to manufacture a flat plate light emitting panel by using the organic EL element.
An illumination apparatus includes a light emitting panel in which a transparent positive electrode layer, an organic luminescence layer and a negative electrode layer are stacked on a transparent substrate (see, e.g., Japanese Patent Application Publication No. 2007-227523). The positive electrode layer and the negative electrode layer are connected to a power supply circuit unit which supplies a driving voltage to the light emitting panel. The negative electrode layer is grounded.
However, in the above-mentioned illumination apparatus, in a case where a common mode noise voltage may be superposed on an AC power, for example, a pulse current created by such a noise voltage may propagate into the light emitting panel, thereby causing instability in the operation of the light emitting panel.